设计模式之工厂模式

问题：写一个程序来创建一个迷宫，需要有房间、墙壁、门等。
1.写一个由两个房间和它们之间的门组成的小迷宫。
（1） 一个枚举类 描述方向

public enum Direction {
    NORTH,SOUTH,EAST,WEST;
}

（2） 相关类

public  abstract class  MapSite {
    abstract void enter();
}

房间

public class Room  extends MapSite{

    private int roomNo;
    private int [] sides=new int[4];
    
    public Room(int roomNo) {
        super();
        this.setRoomNo(roomNo);
    }

    @Override
    public void enter() {}

    public MapSite getSide(Direction direction) {
        return null;
        
    }
    public void setSide(Direction direction,MapSite mapSite) {
        
    }

    public int getRoomNo() {
        return roomNo;
    }

    public void setRoomNo(int roomNo) {
        this.roomNo = roomNo;
    }

    public int [] getSides() {
        return sides;
    }

    public void setSides(int [] sides) {
        this.sides = sides;
    }
    
}

墙

public class Wall  extends  MapSite{
    
    @Override
    void enter() {
        
    }

}

门

public class Door  extends MapSite{

    private Room room1;
    private Room room2;
    private boolean isOpened;
    
    public Door(Room room1, Room room2) {
        super();
        this.setRoom1(room1);
        this.setRoom2(room2);
    }

    @Override
    void enter() {
        
    }
    
    public Room otherSideFrom(Room room) {
        return room;
    }

    public boolean isOpened() {
        return isOpened;
    }

    public void setOpened(boolean isOpened) {
        this.isOpened = isOpened;
    }

    public Room getRoom1() {
        return room1;
    }

    public void setRoom1(Room room1) {
        this.room1 = room1;
    }

    public Room getRoom2() {
        return room2;
    }

    public void setRoom2(Room room2) {
        this.room2 = room2;
    }

}

迷宫

public class Maze {
    private List<Room> rooms;

    public void addRoom(Room room) {
        rooms.add(room);
    }

}

（3）生成迷宫

public class MazeGame  {
    //生成一个迷宫
    public Maze createMaze() {
        Maze maze=new Maze();
        Room r1=new Room(0);
        Room r2=new Room(1);
        Door door=new Door(r1,r2);
        
        r1.setSide(Direction.NORTH, new Wall());
        r1.setSide(Direction.SOUTH, door);
        r1.setSide(Direction.EAST, new Wall());
        r1.setSide(Direction.WEST, new Wall());
        
        r2.setSide(Direction.NORTH, new Wall());
        r2.setSide(Direction.SOUTH, new Wall());
        r2.setSide(Direction.EAST, new Wall());
        r2.setSide(Direction.WEST, door);
        
        maze.addRoom(r1);
        maze.addRoom(r2);
        return maze;
    }
    
}

有个工厂模式之后

public class MazeFactory {
    public Maze makeMaze() {
        return new Maze();
    }
    
    public Wall makeWall() {
        return new Wall();
    }
    
    public Room makeRoom(int no) {
        return new Room(no);
    }
    
    public Door makeDoor(Room r1,Room r2) {
        return new Door(r1, r2);
    }
}

public class MazeGame {
  //生成一个迷宫
    public Maze createMaze(MazeFactory factory) {
        Maze maze=factory.makeMaze();
        Room r1=factory.makeRoom(0);
        Room r2=factory.makeRoom(1);
        Door door=factory.makeDoor(r1, r2);
        
        r1.setSide(Direction.NORTH, factory.makeWall());
        r1.setSide(Direction.SOUTH, door);
        r1.setSide(Direction.EAST, factory.makeWall());
        r1.setSide(Direction.WEST, factory.makeWall());
        
        r2.setSide(Direction.NORTH, factory.makeWall());
        r2.setSide(Direction.SOUTH, factory.makeWall());
        r2.setSide(Direction.EAST, factory.makeWall());
        r2.setSide(Direction.WEST, door);
        
        maze.addRoom(r1);
        maze.addRoom(r2);
        return maze;
    }
}

原先创建迷宫是一种硬编码，缺乏灵活性，试想你想写一个稍微复杂一点的迷宫，对原先的代码就要做很多的编码，改了这里改那里，写很多重复的代码。有了工厂模式之后，流水线生产，简单易操作。